The present invention relates to an automatic or semiautomatic connection device for connecting a secondary circuit to a drilling element, for the purpose of allowing circulation of fluids in the well during the entire drilling process.
Such a connection device allows connecting the secondary circuit for the circulation of drilling fluids, which in turn is connected to a collector circuit, to a drilling element comprising at least one radial aperture with which at least one valve assembly is associated, so as to allow the drilling fluids to circulate through said radial aperture as is known to those skilled in the art, in order to allow circulation of drilling fluids also during the steps of adding or removing at least one drilling element to/from the string of drilling elements placed in a wellbore.
The connection device is connected to the end of said secondary circuit for the circulation of drilling fluids.
Connection devices are known which are adapted to connect a secondary circuit to a radial aperture comprised in a drilling element in order to allow for continuous circulation of drilling fluids even when adding or removing at least one drilling element to/from the string of drilling elements placed in the wellbore.
Manual connection devices are known, which are manually secured to the drilling element by an operator working on a drill floor of a drilling rig.
Semiautomatic connection devices are also known, which can automatically perform a number of operations for connecting the secondary circuit to the radial aperture under the supervision of an operator, who still has to carry out some manual operations, such as, for example, removing the safety plug normally associated with the radial aperture.
Automatic systems are also known which can automatically connect the secondary circuit to the radial aperture.
Such connection devices employ automatic devices for removing the safety plug. The automatic connection devices known in the art are very complex due to the fact that they need to remove said safety plug from the radial aperture.
Said connection devices also comprise clamping systems that cannot ensure proper sealing between the connection device and the drilling element in case of variations of a radial dimension, e.g. the outside diameter, of the drilling element to be used in the drilling process.
One example of such a connection device is shown in prior-art documents U.S. Pat. No. 8,033,338 and U.S. Pat. No. 8,016,033. The solutions proposed therein are very complex and require very long times for establishing the connection and allow the circulation of drilling fluids through said radial aperture.
In both solutions described in the above-mentioned patent documents, a very accurate control of the positioning of the radial aperture relative to said connection device is required, thus being hardly applicable to an existing rig. Moreover, because of the complexity of these devices, both solutions require that the mud intake duct be positioned not in alignment with the radial aperture, leading to a number of problems known to those skilled in the art.
Prior-art document US2013068532 describes an automatic connection device comprising an actuating device for lifting a gate-type obstructor comprised in a valve assembly associated with a radial aperture of a drilling element. Said obstructor is adapted to close said radial aperture. In this case as well, the connection device requires a perfect alignment between the radial aperture and the device itself to ensure a proper connection of the device to the drilling element.
The clamping system described in this latter document is not capable of automatically exerting a sealing force on the drilling element also when the radial dimensions of the drilling element change. In this case as well, the presence of an operator is required, who will have to secure the clamping system around the drilling element.
In all of the solutions described in prior-art documents, although substantially linear movements are only made, the handling devices are very complex because of the necessity of removing a safety plug or lifting gates, at any rate requiring the active presence of an operator near the drilling element while connecting or disconnecting the secondary circuit.
All connection devices require an excessively long time for properly connecting the device to the drilling element, in particular for ensuring that the radial aperture will open safely, due to the valve assembly being associated with the radial aperture of the drilling element. In fact, such valve assemblies offer poor performance in terms of safety of opening and closing said radial aperture, which the connection device itself must make up for in order to ensure proper circulation of drilling fluids through said radial aperture.
The high complexity of prior-art connection devices increases the risk of a malfunction and requires longer repair times.